For example we've got a buffer solution below:HA <-------> H^+ + A^-NaA -------> Na^+ + A^-By adding NaOH (Na^+ and OH^-) to the solution , OH^- would react with H^+ and H^+ decreases. so the equilibrium turns right to increase [H^+] again . so [H^+] doesn't change much.That's our buffer solution.The question is what is the role of our salt HERE ?

Please explain the role of NaA in MY example. I know the roll of salt when you add an acid. But i don't know NaA's role when adding a base (OH^-)

I used to know the answer but i can't remember it... ... something about Ka ...